ChapterÂ 12.Â
Add a channel information service

Typing multicast addresses is not very fun... that's why you need
a channel information service ! VideoLAN has implemented a channel
information service based on the SAP/SDP standard. The SAP announces
about the multicast programs are sent on the network (via the multicast
address 224.2.127.254 reserved for this purpose).
On the client side, VLCs receive these annouces and automatically add
the programs announced to their playlist.

VLC can send the SAP announces associated with the programs
it is streaming. VLS can't do that, but an independant program, the
mini-SAP-server, can send the announces for the programs sent by
VLS.

Send announces when streaming with VLC

To send announces with VLC, you need to use the complex syntax of
VLC's stream output, like this:

where video1.xyz is the file you want
to stream, 239.255.12.42 is the multicast IP
address you want to stream on, Test Stream is
the name that will be used for this program in the SAP announces and
12 is the value of the TTL (Time To Live) of the
stream and of the SAP announces.

Install the mini-SAP-server

Configure the mini-SAP-server

Edit the configuration file sap.cfg shipped
with the tarball. It should contain a global section with the Time To
Live (TTL) and the IP version (IPv4 or IPv6) used for the SAP announces
and a section per program announced. Use the comments to understand each
parameter.

The Time To Live option indicates the maximum number of routers
that the SAP announce packets can cross before being dropped.

Run the mini-SAP-server

Start the mini-SAP-server:

% ./sapserver -c sap.cfg

If you want to run the mini-SAP-server in the
background, use the -d command line switch. For
instance:

% ./sapserver -d -c sap.cfg

You can also omit the -c
command line switch if your config file is /etc/sap.cfg.

Start VLC(s) on the client(s)

If the announces are sent in IPv4 :

% vlc -vvv --extraintf sap

If the announces are sent in IPv6 :

% vlc -vvv --extraintf sap --sap-ipv6

Then open the playlist: you should see the names of the programs
announced in SAP. When you double-click on the name of a program,
VLC will subscribe to the multicast address and start to play the stream
!